Message to Fred and Mark -
1. You do not have to match salaries in a sign and trade if you are the under-cap.
2. The history of sign and trades is that the team losing the major player does not get anywhere near equal value in return.
http://www.blogabull.com/2010/3/4/1356662/recent-history-of-sign-and-trades
UNRESTRICTED FAs:
Hedo Turkoglu to the Raptors for a trade exception. The Raptors had cap space to sign him outright, but the Magic agreed to make it a sign-and-trade for nothing in order to land a trade exception.
Rashard Lewis to the Magic for a 2nd round pick. The Magic had the cap space to offer a 5-year max deal with Lewis, but Lewis wanted a 6th year, causing his S&T for a 2nd round pick.
Peja Stojakovic to the Hornets for a trade exception. The Hornets had plenty of cap space, but the Pacers didn't want to lose Peja for nothing. So they offered the Hornets $250k to persuade them to acquire Peja via sign-and trade instead, allowing them to get...
Al Harrington to the Pacers for a 1st round pick. The Pacers did not have cap space, but neither did any other option after the Bulls signed Ben Wallace and the Hornets traded for Peja. The Pacers though had their trade exception, making them "the only Harrington suitor that could complete a sign-and-trade without forcing Atlanta to take back significant salary." The Hawks were slashing salary after ownership issues, and the Pacers got Harrington for a 1st round pick.
Brad Miller to the Kings for Scott Pollard and a trade exception. This is the only example I could find of the "use other teams with cap space as leverage" idea posed by tyger and Mike McGraw. The Nuggets and Jazz had cap space and offered big contracts to Miller, but Miller wanted to join the contending, over the cap Kings, and the Pacers jumped at the trade instead of losing Miller for nothing.
Grant Hill to the Magic for Chucky Atkins and Ben Wallace. This goes far enough back where the details get a bit sketchy, but it looks like the Magic had enough cap room to sign two max FA's outright and agreed to a sign-and-trade to give Hill a 7-year max deal.
Tracy McGrady to the Magic for a 1st round pick. Sketchier again, as I can't remember or find out why McGrady was traded for so little despite being just a 3rd year player. I'm assuming he was unrestricted. The Magic had just brought in Hill and still had the cap room to sign McGrady, and they again agreed to S&T to give McGrady the full 7-year contract.
RESTRICTED FAs:
Restricted FAs require sign-and-trades if the acquiring team wants to avoid the offer sheet process, so their cost has been higher.
Joe Johnson to the Hawks for Boris Diaw and two 1sts. The Hawks had the cap space for Johnson's 5-year, $70 mil deal. The Suns were considering matching the offer (JJ was a restricted FA), but chose to honor Johnson's wish and let him walk in exchange for Diaw and two 1sts.
Eddy Curry to the Knicks for a 1st and a right to swap another 1st. Bulls had the right to match any offer, the Knicks wanted him, so he was swapped essentially for what became Tyrus and Noah. The Knicks were above the cap when this happened.
Kenyon Martin to the Nuggets for three 1st round picks. The Nuggets had the cap space for a max deal, but because Martin was restricted, they paid the Nets 3 first-round picks as compensation.
3. If Bosh decides he wants to come to Chicago, Toronto has no leverage. They would be better off getting a trade exception than taking on a contract
I usually agree with you Fred, but you are dead wrong about sign and trades.